To start: we are using exchange 2010 with spam assassin. Some of our users are experiencing a rise in junk spam emails for about two weeks now. Most of these junk emails even get to the normal inbox without being classified as junk.
These users have no mailing list in common, that is why we are puzzled. Our guess is that these users used their corporate email addresses to sign up on some site or petition or something like that.
Since we are receiving a lot of "feedback" from these users which takes up too much time lately is there anything we could do except block the senders email address and IP?
Every idea is much appreciated!